fr.cnes.sirius.patrius.math.analysis

Class FunctionUtils

java.lang.Object

fr.cnes.sirius.patrius.math.analysis.FunctionUtils

public final class FunctionUtils
extends Object

Utilities for manipulating function objects.

Since:

3.0

Version:

$Id: FunctionUtils.java 18108 2017-10-04 06:45:27Z bignon $

Method Summary

Modifier and Type	Method and Description
static UnivariateDifferentiableFunction	add(UnivariateDifferentiableFunction... f) Adds functions.
static UnivariateFunction	add(UnivariateFunction... f) Adds functions.
static MultivariateFunction	collector(BivariateFunction combiner, double initialValue) Returns a MultivariateFunction h(x[]) defined by
static MultivariateFunction	collector(BivariateFunction combiner, UnivariateFunction f, double initialValue) Returns a MultivariateFunction h(x[]) defined by
static UnivariateFunction	combine(BivariateFunction combiner, UnivariateFunction f, UnivariateFunction g) Returns the univariate function h(x) = combiner(f(x), g(x)).
static UnivariateDifferentiableFunction	compose(UnivariateDifferentiableFunction... f) Composes functions.
static UnivariateFunction	compose(UnivariateFunction... f) Composes functions.
static UnivariateFunction	fix1stArgument(BivariateFunction f, double fixed) Creates a unary function by fixing the first argument of a binary function.
static UnivariateFunction	fix2ndArgument(BivariateFunction f, double fixed) Creates a unary function by fixing the second argument of a binary function.
static UnivariateDifferentiableFunction	multiply(UnivariateDifferentiableFunction... f) Multiplies functions.
static UnivariateFunction	multiply(UnivariateFunction... f) Multiplies functions.
static double[]	sample(UnivariateFunction f, double min, double max, int n) Samples the specified univariate real function on the specified interval.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

compose

public static UnivariateFunction compose(UnivariateFunction... f)

Composes functions.
The functions in the argument list are composed sequentially, in the given order. For example, compose(f1,f2,f3) acts like f1(f2(f3(x))).

Parameters:

f - List of functions.

Returns:

the composite function.

compose

public static UnivariateDifferentiableFunction compose(UnivariateDifferentiableFunction... f)

Composes functions.
The functions in the argument list are composed sequentially, in the given order. For example, compose(f1,f2,f3) acts like f1(f2(f3(x))).

Parameters:

f - List of functions.

Returns:

the composite function.

Since:

3.1

add

public static UnivariateFunction add(UnivariateFunction... f)

Adds functions.

Parameters:

f - List of functions.

Returns:

a function that computes the sum of the functions.

add

public static UnivariateDifferentiableFunction add(UnivariateDifferentiableFunction... f)

Adds functions.

Parameters:

f - List of functions.

Returns:

a function that computes the sum of the functions.

Since:

3.1

multiply

public static UnivariateFunction multiply(UnivariateFunction... f)

Multiplies functions.

Parameters:

f - List of functions.

Returns:

a function that computes the product of the functions.

multiply

public static UnivariateDifferentiableFunction multiply(UnivariateDifferentiableFunction... f)

Multiplies functions.

Parameters:

f - List of functions.

Returns:

a function that computes the product of the functions.

Since:

3.1

combine

public static UnivariateFunction combine(BivariateFunction combiner,
                                         UnivariateFunction f,
                                         UnivariateFunction g)

Returns the univariate function
h(x) = combiner(f(x), g(x)).

Parameters:

combiner - Combiner function.

f - Function.

g - Function.

Returns:

the composite function.

collector

public static MultivariateFunction collector(BivariateFunction combiner,
                                             UnivariateFunction f,
                                             double initialValue)

Returns a MultivariateFunction h(x[]) defined by

 
 h(x[]) = combiner(...combiner(combiner(initialValue,f(x[0])),f(x[1]))...),f(x[x.length-1]))
 
 

Parameters:

combiner - Combiner function.

f - Function.

initialValue - Initial value.

Returns:

a collector function.

collector

public static MultivariateFunction collector(BivariateFunction combiner,
                                             double initialValue)

Returns a MultivariateFunction h(x[]) defined by

 
 h(x[]) = combiner(...combiner(combiner(initialValue,x[0]),x[1])...),x[x.length-1])
 
 

Parameters:

combiner - Combiner function.

initialValue - Initial value.

Returns:

a collector function.

fix1stArgument

public static UnivariateFunction fix1stArgument(BivariateFunction f,
                                                double fixed)

Creates a unary function by fixing the first argument of a binary function.

Parameters:

f - Binary function.

fixed - Value to which the first argument of f is set.

Returns:

the unary function h(x) = f(fixed, x)

fix2ndArgument

public static UnivariateFunction fix2ndArgument(BivariateFunction f,
                                                double fixed)

Creates a unary function by fixing the second argument of a binary function.

Parameters:

f - Binary function.

fixed - Value to which the second argument of f is set.

Returns:

the unary function h(x) = f(x, fixed)

sample

public static double[] sample(UnivariateFunction f,
                              double min,
                              double max,
                              int n)

Samples the specified univariate real function on the specified interval.
The interval is divided equally into n sections and sample points are taken from min to max - (max - min) / n; therefore f is not sampled at the upper bound max.

Parameters:

f - Function to be sampled

min - Lower bound of the interval (included).

max - Upper bound of the interval (excluded).

n - Number of sample points.

Returns:

the array of samples.

Throws:

NumberIsTooLargeException - if the lower bound min is greater than, or equal to the upper bound max.

NotStrictlyPositiveException - if the number of sample points n is negative.